ipv4: Check return of dev_set_allmulti

allmulti might overflow.
Commit: "netdevice: Fix promiscuity and allmulti overflow" in net-next makes
dev_set_promiscuity/allmulti return error number if overflow happened.

Here, we check the positive increment for allmulti to get error return.

PS: For unwinding tunnel creating, we let ipip->ioctl() to handle it.

Signed-off-by: Wang Chen <wangchen@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 39 insertions, 1 deletions

diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 438fab9c62a0..2f4d8afd067c 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -118,6 +118,31 @@ static struct timer_list ipmr_expire_timer;
 
 /* Service routines creating virtual interfaces: DVMRP tunnels and PIMREG */
 
+static void ipmr_del_tunnel(struct net_device *dev, struct vifctl *v)
+{
+        dev_close(dev);
+
+        dev = __dev_get_by_name(&init_net, "tunl0");
+        if (dev) {
+                struct ifreq ifr;
+                mm_segment_t    oldfs;
+                struct ip_tunnel_parm p;
+
+                memset(&p, 0, sizeof(p));
+                p.iph.daddr = v->vifc_rmt_addr.s_addr;
+                p.iph.saddr = v->vifc_lcl_addr.s_addr;
+                p.iph.version = 4;
+                p.iph.ihl = 5;
+                p.iph.protocol = IPPROTO_IPIP;
+                sprintf(p.name, "dvmrp%d", v->vifc_vifi);
+                ifr.ifr_ifru.ifru_data = (__force void __user *)&p;
+
+                oldfs = get_fs(); set_fs(KERNEL_DS);
+                dev->do_ioctl(dev, &ifr, SIOCDELTUNNEL);
+                set_fs(oldfs);
+        }
+}
+
 static
 struct net_device *ipmr_new_tunnel(struct vifctl *v)
 {
@@ -389,6 +414,7 @@ static int vif_add(struct vifctl *vifc, int mrtsock)
         struct vif_device *v = &vif_table[vifi];
         struct net_device *dev;
         struct in_device *in_dev;
+        int err;
 
         /* Is vif busy ? */
         if (VIF_EXISTS(vifi))
@@ -406,18 +432,31 @@ static int vif_add(struct vifctl *vifc, int mrtsock)
                 dev = ipmr_reg_vif();
                 if (!dev)
                         return -ENOBUFS;
+                err = dev_set_allmulti(dev, 1);
+                if (err) {
+                        unregister_netdevice(dev);
+                        return err;
+                }
                 break;
 #endif
         case VIFF_TUNNEL:
                 dev = ipmr_new_tunnel(vifc);
                 if (!dev)
                         return -ENOBUFS;
+                err = dev_set_allmulti(dev, 1);
+                if (err) {
+                        ipmr_del_tunnel(dev, vifc);
+                        return err;
+                }
                 break;
         case 0:
                 dev = ip_dev_find(&init_net, vifc->vifc_lcl_addr.s_addr);
                 if (!dev)
                         return -EADDRNOTAVAIL;
                 dev_put(dev);
+                err = dev_set_allmulti(dev, 1);
+                if (err)
+                        return err;
                 break;
         default:
                 return -EINVAL;
@@ -426,7 +465,6 @@ static int vif_add(struct vifctl *vifc, int mrtsock)
         if ((in_dev = __in_dev_get_rtnl(dev)) == NULL)
                 return -EADDRNOTAVAIL;
         IPV4_DEVCONF(in_dev->cnf, MC_FORWARDING)++;
-        dev_set_allmulti(dev, +1);
         ip_rt_multicast_event(in_dev);
 
         /*